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Cambridge IGCSE™
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CHEMISTRY
0620/42
Paper 4 Theory (Extended)
May/June 2024
1 hour 15 minutes
You must answer on the question paper.
No additional materials are needed.
INSTRUCTIONS
●
Answer all questions.
●
Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs.
●
Write your name, centre number and candidate number in the boxes at the top of the page.
●
Write your answer to each question in the space provided.
●
Do not use an erasable pen or correction fluid.
●
Do not write on any bar codes.
●
You may use a calculator.
●
You should show all your working and use appropriate units.
INFORMATION
●
The total mark for this paper is 80.
●
The number of marks for each question or part question is shown in brackets [ ].
●
The Periodic Table is printed in the question paper.
This document has 16 pages. Any blank pages are indicated.
IB24 06_0620_42/4RP
© UCLES 2024
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2
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A list of gases is shown.
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ammonia
helium
hydrogen
carbon dioxide
carbon monoxide
chlorine
methane
nitrogen dioxide
propene
sulfur dioxide
Answer the following questions about these gases.
Each gas may be used once, more than once or not at all.
(a) State one gas which:
(i)
is the main constituent of natural gas
....................................................................................................................................... [1]
(ii)
is responsible for both photochemical smog and acid rain
....................................................................................................................................... [1]
(iii)
is unsaturated
....................................................................................................................................... [1]
(iv)
has monatomic particles
....................................................................................................................................... [1]
(v)
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1
reduces iron(III) oxide in a blast furnace.
....................................................................................................................................... [1]
(b) Nitrogen dioxide, NO2, and carbon monoxide are removed from a car exhaust by a catalytic
converter.
Write the symbol equation for this reaction.
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,
[Total: 7]
© UCLES 2024
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0620/42/M/J/24
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.............................................................................................................................................. [2]
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3
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2
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A list of five metals is shown.
copper
iron
magnesium
potassium
silver
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(a) All metals form positive ions.
(i)
Describe how atoms form positive ions.
....................................................................................................................................... [1]
(ii)
State which of the five metals in the list has the greatest tendency to form positive ions.
....................................................................................................................................... [1]
(iii)
Suggest one of the five metals in the list which is not likely to show catalytic properties.
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....................................................................................................................................... [1]
(iv)
State which of the five metals in the list is a major component of stainless steel.
....................................................................................................................................... [1]
(b) A student adds a sample of a metal to an aqueous metal salt in a beaker to see if a displacement
reaction takes place.
Complete Table 2.1 to show the colour of the solution in the beaker at the start and at the end
of the experiment.
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Table 2.1
metal
aqueous solution
colour at the start
magnesium
iron(II) sulfate
green
silver
copper(II) sulfate
colour at the end
[3]
© UCLES 2024
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0620/42/M/J/24
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(c) Most Group II metals form a gas when placed into cold water. An alkaline solution is also
formed.
(i)
Name the gas formed when strontium is added to cold water.
....................................................................................................................................... [1]
(ii)
Name the alkaline solution formed when strontium is added to cold water.
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* 0019654852404 *
One Group II metal reacts very slowly when placed in cold water. When heated, the metal
reacts with steam to form a white solid.
Identify this metal and name the white solid formed.
metal ...................................................................................................................................
white solid ...........................................................................................................................
[2]
(d) Under certain conditions, iron will react with steam to form an oxide of iron with the formula
Fe3O4.
Fe3O4 reacts with dilute hydrochloric acid to form a mixture of iron(II) and iron(III) salts and
water.
Deduce the symbol equation for the reaction between Fe3O4 and dilute hydrochloric acid.
.............................................................................................................................................. [3]
© UCLES 2024
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0620/42/M/J/24
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[Total: 14]
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(iii)
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....................................................................................................................................... [1]
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5
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3
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The symbol equation for the industrial production of ammonia is shown.
N2(g) + 3H2(g)
2NH3(g)
∆H = –90 kJ / mol
(a) Name this industrial process.
.............................................................................................................................................. [1]
.............................................................................................................................................. [1]
(c) State the typical conditions and name the catalyst used in the industrial production of ammonia.
temperature and units ........................................
pressure and units .............................................
catalyst used ......................................................
[3]
(d) State two methods of increasing the rate of this reaction.
1 .................................................................................................................................................
2 .................................................................................................................................................
[2]
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(b) State the meaning of ∆H.
© UCLES 2024
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(e) The symbol equation for the reaction can be represented as shown in Fig. 3.1.
N
H
N + H
H
H
H
H H
N
H
H
+
H
N
H
H
H = –90 kJ / mol
Fig. 3.1
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* 0019654852406 *
Table 3.1
bond
N≡N
H–H
bond energy in kJ / mol
945
435
Use the bond energies in Table 3.1 and ∆H to calculate the bond energy of an N–H bond, in
kJ / mol.
Use the following steps.
.............................. kJ
Calculate the energy released when bonds form in the products.
.............................. kJ
●
Calculate the energy of an N–H bond.
.............................. kJ / mol
[3]
© UCLES 2024
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Calculate the energy needed to break bonds in the reactants.
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Table 3.1 shows some bond energies.
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* 0019654852407 *
7
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(f) An incomplete symbol equation for the preparation of ammonia in the laboratory is shown.
CaO + 2NH4Cl → CaCl 2 + ......................... + 2NH3
(i)
Complete the symbol equation.
(ii)
Name NH4Cl.
[1]
(iii)
Calculate the volume of ammonia, NH3, measured at room temperature and pressure,
which forms when 1.12 g of CaO is heated with excess NH4Cl.
[Mr: CaO, 56]
.............................. cm3 [3]
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[Total: 15]
© UCLES 2024
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4
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A carboxylic acid reacts with an alcohol to produce an ester and water.
Under certain conditions, this reaction can be reversed so an ester reacts with water to produce a
carboxylic acid X and an alcohol Y.
The reaction reaches an equilibrium.
CH3CH2COOCH3 + H2O
X + Y
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(a) Deduce the empirical formula of the ester.
.............................................................................................................................................. [1]
(b) Name the ester.
.............................................................................................................................................. [1]
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The forward reaction is endothermic.
name ..........................................................................................................................................
displayed formula
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(c) Name carboxylic acid X and draw its displayed formula.
name ..........................................................................................................................................
structural formula .......................................................................................................................
[2]
© UCLES 2024
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0620/42/M/J/24
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(d) Name alcohol Y and give its structural formula.
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[2]
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* 0019654852509 *
9
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(e) Complete Table 4.1 to show the effect, if any, for each change of condition.
Table 4.1
effect on the concentration of
carboxylic acid X at equilibrium
change of condition
temperature is decreased
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concentration of CH3CH2COOCH3
is decreased
more alcohol Y is added
a catalyst is added
[4]
(f) At the beginning of the reaction between the ester and water, no carboxylic acid is present in
the reaction mixture.
(i)
pH at start of reaction .........................................................................................................
pH at equilibrium .................................................................................................................
[2]
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(ii)
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Suggest how the pH of the reaction mixture changes from the start of the reaction until
equilibrium is reached.
Assume alcohols and esters are neutral.
Identify the ion that causes the change in pH.
....................................................................................................................................... [1]
(iii)
Name an indicator which can be used to follow the change in pH.
....................................................................................................................................... [1]
[Total: 14]
© UCLES 2024
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0620/42/M/J/24
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Sulfur is a Group VI element.
(a) A sample of sulfur contains two isotopes, 32S and 34S.
Complete Table 5.1 to show the number of protons and neutrons in one atom of each
isotope of sulfur.
Table 5.1
32
S
34
S
protons
neutrons
[2]
(ii)
State why these isotopes have identical chemical properties.
....................................................................................................................................... [1]
(iii)
State the mass of 6.02 × 1023 atoms of 34S. Include units in your answer.
....................................................................................................................................... [1]
(iv)
State the name of the amount of substance which contains 6.02 × 1023 atoms.
....................................................................................................................................... [1]
(v)
Table 5.2 shows the relative abundance of these isotopes of sulfur in the sample.
Table 5.2
atom
32
S
34
relative abundance
95%
5%
S
Calculate the relative atomic mass of sulfur in this sample to one decimal place.
relative atomic mass = .............................. [2]
© UCLES 2024
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(i)
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(b) Sulfur reacts with magnesium to form magnesium sulfide, MgS, an ionic compound.
(i)
Complete the dot-and-cross diagram in Fig. 5.1 of the ions in magnesium sulfide.
Give the charges on the ions.
........
........
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Mg
Fig. 5.1
(ii)
[3]
State why MgS has a high melting point.
....................................................................................................................................... [1]
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(iii)
State why molten MgS conducts electricity.
....................................................................................................................................... [1]
(c) An acid containing sulfur reacts with sodium hydroxide, NaOH, to form a salt and water. The
salt has the formula Na2SO3.
(i)
Deduce the formula of this acid.
....................................................................................................................................... [1]
(ii)
Deduce the formula of the anion in Na2SO3.
....................................................................................................................................... [1]
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S
(d) Na2SO3 is oxidised by acidified aqueous potassium manganate(VII).
(i)
State what VII refers to in the name potassium manganate(VII).
....................................................................................................................................... [1]
(ii)
.
© UCLES 2024
State the colour change when this reaction happens.
from ............................................................ to ............................................................. [2]
[Total: 17]
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12
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Glucose is involved in two processes.
(a) Glucose, C6H12O6, is made in plants from carbon dioxide and water.
Name this process.
....................................................................................................................................... [1]
Write the symbol equation for this process.
....................................................................................................................................... [1]
(iii)
State two essential conditions needed for this process to happen.
1 ..........................................................................................................................................
2 ..........................................................................................................................................
[2]
(b) Glucose is converted to ethanol.
(i)
Name this process.
....................................................................................................................................... [1]
(ii)
Name the other product formed when glucose is converted to ethanol.
....................................................................................................................................... [1]
(c) Ethanol is made by reacting ethene with steam in an industrial process.
(i)
State the conditions and type of catalyst used in this industrial production of ethanol.
temperature and units ...........................................
pressure and units ................................................
type of catalyst used .............................................
(ii)
[3]
Explain why this reaction is an addition reaction.
....................................................................................................................................... [1]
© UCLES 2024
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(ii)
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(i)
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6
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* 0019654852512 *
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13
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(iii)
,
Complete the dot-and-cross diagram in Fig. 6.1 of a molecule of ethanol.
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H
H
H
C
C
H
H
Fig. 6.1
O
H
[3]
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[Total: 13]
© UCLES 2024
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© UCLES 2024
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BLANK PAGE
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15
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* 0019654852515 *
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge
Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download
at www.cambridgeinternational.org after the live examination series.
Cambridge Assessment International Education is part of Cambridge Assessment. Cambridge Assessment is the brand name of the University of Cambridge
Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge.
© UCLES 2024
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© UCLES 2024
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24
25
27
28
29
30
73
72
57–71
lanthanoids
56
–
–
cerium
140
90
Th
thorium
232
lanthanum
139
89
Ac
actinium
–
231
protactinium
Pa
91
141
praseodymium
Pr
59
58
Ce
57
–
–
La
Db
dubnium
Rf
Sg
238
uranium
U
92
144
neodymium
Nd
60
–
seaborgium
–
neptunium
Np
93
–
promethium
Pm
61
–
bohrium
Bh
107
186
rhenium
Re
75
–
technetium
Tc
43
–
plutonium
Pu
94
150
samarium
Sm
62
–
hassium
Hs
108
190
osmium
Os
76
101
ruthenium
Ru
44
56
iron
–
americium
Am
95
152
europium
Eu
63
–
meitnerium
Mt
109
192
iridium
Ir
77
103
rhodium
Rh
45
59
cobalt
–
curium
Cm
96
157
gadolinium
Gd
64
–
darmstadtium
Ds
110
195
platinum
Pt
78
106
palladium
Pd
46
59
nickel
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–
berkelium
Bk
97
159
terbium
Tb
65
–
roentgenium
Rg
111
197
gold
Au
79
108
silver
Ag
47
64
copper
–
einsteinium
Es
99
165
holmium
Ho
67
–
nihonium
Nh
113
204
thallium
Tl
81
115
indium
In
49
70
gallium
114
–
fermium
Fm
100
167
erbium
Er
68
–
flerovium
Fl
–
115
207
–
mendelevium
Md
101
169
thulium
Tm
–
–
–
–
lawrencium
Lr
103
175
lutetium
Lu
71
Og
oganesson
Ts
tennessine
118
–
radon
Rn
86
131
xenon
Xe
54
84
krypton
Kr
36
40
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nobelium
No
102
173
ytterbium
Yb
70
–
–
69
Lv
livermorium
Mc
moscovium
117
–
209
lead
116
At
astatine
Po
polonium
Bi
bismuth
Pb
85
127
iodine
I
53
80
bromine
84
128
tellurium
Te
52
79
selenium
Br
35
83
122
antimony
Sb
51
75
arsenic
Se
34
82
119
tin
Sn
50
73
germanium
As
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–
californium
Cf
98
163
dysprosium
Dy
66
–
copernicium
Cn
112
201
mercury
Hg
80
112
cadmium
Cd
48
65
zinc
Ge
33
,
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The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.).
actinoids
lanthanoids
Ra
radium
Fr
francium
106
184
tungsten
W
74
96
molybdenum
Mo
42
55
manganese
Ga
32
argon
Ar
18
20
neon
Ne
16
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0620/42/M/J/24
rutherfordium
105
104
actinoids
181
178
89–103
88
87
137
133
Ta
tantalum
Ba
barium
Cs
caesium
Hf
93
niobium
Nb
hafnium
91
55
zirconium
89
88
85
yttrium
strontium
rubidium
Zr
Y
Sr
41
52
chromium
Zn
Rb
40
39
51
vanadium
Cu
38
48
45
Ni
37
titanium
scandium
Co
40
Fe
calcium
Mn
39
V
Cr
potassium
Ti
Sc
Ca
26
K
23
31
22
21
20
35.5
32
31
28
19
chlorine
sulfur
phosphorus
silicon
27
24
23
aluminium
magnesium
sodium
Cl
S
P
Si
Al
Mg
Na
17
16
15
14
13
12
11
19
16
14
12
11
relative atomic mass
9
7
F
fluorine
O
oxygen
N
nitrogen
C
carbon
B
name
boron
atomic symbol
Be
beryllium
Li
lithium
10
4
9
1
8
helium
hydrogen
7
2
He
1
VIII
,
H
6
VII
5
VI
atomic number
V
4
IV
3
Key
III
II
I
Group
The Periodic Table of Elements
* 0019654852516 *